Tofu is a high vegetable based protein food free of cholesterol, low in saturated fats, and relatively low in calories. It is a useful food, especially for those watching their weight, concerned about heart problems or high blood pressure. It is prepared from soybeans. In 1979, Japan's largest tofu factories used 15 tons of American dry soybeans each day to produce 45 to 60 tons of tofu daily. The method of tofu production of the largest modern factories is still the traditional Chinese step-by-step batch process which has been used for thousands of years. The steps for making tofu as described in Shurtleff's book are as follows: (1) clean soybeans, (2) wash and soak, (3) drain, (4) grind, (5) extract, (6) cook soymilk, (7) coagulate, (8) remove supernatant whey from the coagulation tank, (9) scoop bean curds into forming box and wrap it with filtercloth, (10) press to remove whey, (11) unwrap the filtercloth and remove tofu from the forming box into water, (12) cut block tofu into small cakes, (13) cool, (14) pick up each tofu cake and put it into a plastic water-filled-tub, and (15) thermoseal.
Tofu contains 85% moisture and actually this moisture is whey. Whey is neither good to the taste nor to one's health. The plastic water-filled-tub package to tofu in the supermarket is awkward looking and even though it has been pasteurized, it still cannot be stored without refrigeration see Levton, Richard, "Spotlight: Retail", SOYFOOD. Because of its high protein content and moisture, tofu is a very good medium for microbes. It is very easily perishable. Even refrigerated, the shelf life of tofu is less than a week, and its freshness keeps only two or three days.